Reverberation loudspeaker



ci. 17, 1967 YASUNORI MOCHIDA TAL 3,347,337

REVERBERAT ION LOUDSPEAKER Filed Feb. 24, 1967 United States Patent Office v3,347,337 Patented Oct. 17, 1967 3,347,337 REVERBERATION LOUDSPEAKER Yasunori Mochida and Kazukiyo Ishimura, Hamamatsushi, Japan, assignors to Nippon Gakki Seizo Kabushiki Kaisha, Shizuoka-ken, Japan Filed Feb. 24, 1967, Ser. No. 618,492 Claims priority, application Japan, May 16, 1966, 41/ 31,027 1 Claim. (Cl. 181-31) ABSTRACT F THE DISCLOSURE The present invention provides a reverberation flat speaker producing a very natural reverberation sound. The yspeaker is provided with a plurality of coil springs. One end of each coil spring is connected to a pin attached on a cap securely positioned at the center of a diaphragm of the speaker and the other to each of pins attached at suitable positions on the diaphragm. Furthermore, each of the coil springs has its own spring constant and natural frequency different from each other. Thus the speaker of the present invention can produce a wide range of reverberation frequencies, offering a remarkably natural reverberation.

The present invention relates to a flat speaker of the type wherein a flat diaphragm secured around the periphery thereof to a supporting frame is driven by means of a driver connected thereto, and more specifically to a reverberation loudspeaker having a plurality of reverberation coil springs one end of each of which is operatively connected to the -central portion of the diaphragm while the other to each of `suitable positions on the diaphragm, thereby producing a very natural reverberation effect from the speaker.

There has been suggested a reverberation cone-speaker wherein one end of a coil spring is connected to a driver while the other to the non-vibrating portion of the speaker or the like. In this construction, vibrational energy is transmitted from the' vibrating end of the spring to the fixed end thereof, and reflected by the fixed end back to the diaphragm again. This vibrational energy transmission cycle is repeated and vibrational energy is radiated from the diaphragm as reverberatory sound. However, since the frequencies adapted to produce reverberatory sound are an integral number times the resonant frequency of a spring respectively, reverberatory sound produced by the above described system is quite un- .natural as compared with the actual three-dimensional reverberation produced in the hall or the like (i.e. the frequency characteristics of reverberatory sound is bad) when the number of springs is only one or two. The frequency characteristics may be improved to some eX- tent by increasing the number of springs, but the mass participating in vibration system is increased so that the radiation elfect or efficiency of the speaker is decreased.

Therefore, a principal object of the present invention is to provide a reverberation iiat speaker having a better reverberation characteristics and being able to produce a very natural reverberation effect.

A further object of the present invention is to provide a reverberation flat speaker comprising a flat diaphragm secured around the periphery thereof to a supporting frame and connected to a driver; and a plurality of coil springs, one end of each coil spring being connected to the central portion of a diaphragm driven by the driver and the other to each of suitable positions of the diaphragm.

A yet further object of the present invention is to pro vide a flat speaker of the type described above wherein said plurality of coil springs have respectively different spring constant and natural frequency so that resonant frequencies thereof may be increased, thereby producing a better reverberation characteristics.

In other that these and other objects of the present invention may be more readily understood, a preferred embodiment will be described with reference to the accompanying drawings, in which:

FIG. 1 is a side elevational view, partly in section, of a reverberation fiat speaker according to the present invention; and

FIG. 2 is a front view thereof.

Referring now to the drawings, the speaker according to the present invention includes a supporting frame 10 adapted to securely support a driver 11 of the conventional type having a voice-coil bobbin 12. The frame 10 has a peripheral tiange 14 extending outwardly so that the outer periphery thereof may securely support a at diaphragm 13 which is substantially rectangular in form. The diaphragm 13 is tightly secured around the outer periphery thereof to the frame 10 by disposing a holding frame 16 around the diaphragm 13 and inserting fastening members 1S through the holding frame 16 into the frame flange 14. The diaphragm 13 is made of foamed polystyrene or plastic material reinforced by reinforcing ber such as glass ber or any other `suitable material. The dimension of the diaphragm is for example, 900 mm. (L) X 650 mm. (W) X 10 mm. (T), and its Weight is in the order of 300 gr. The center of the diap-hragm is covered by a cap 17 secured thereupon, and is operatively connected with the voice-coil bobbin 12 of the driver 11. A plurality of reverberation coil springs 18 having respectively spring constant and natural frequency different from each other are positioned so as to extend radially from the center of the diaphragm. One end of each spring 18 is securely connected to a pin 19 provided on the cap 17 positioned at the center of the diaphragm 13 while the other to each of pins 20 provided on the diaphragm 13.

Now the operation of the reverberation flat speaker having the above described system will be described hereinafter. Vibrational energy generated by the Voicecoil bobbin 12 of the driver 11 is transmitted to the diaphragm 13 and radiated therefrom as sound. At the same time vibrational energy is also transmitted to the springs 18 from the central ends and then to the outer ends thereof with a slight time delay whereby vibrational energy is transmitted to the diaphragm at the proximities of the outer ends of the springs 18. At the same time vibrational energy of the diaphragm there is reiiected back to the springs 18 and returned to the center of the diaphragm, thereby causing the diaphragm 13 to vibrate. At the same time Isuch vibrational energy is transmitted in turn through the spring back to the outer end thereof thereby vibrating the diaphragm 13 again at the proximities of the outer ends of the springs 18. Such cyclic operation accompanied with damping is re- 3 peated so that a remarkably natural reverberation can be produced from the speaker.

It will be understood that other modifications may be made in the present invention by those iskilled in the art without departing from the spirit of it.

What is claimed is:

A reverberation flat speaker wherein a fiat diaphragm is secured around the periphery thereof to a supporting frame characterized in that one ends of a plurality of References Cited UNITED STATES PATENTS Midhat 181--31 Knoblaugh 179-1 Martin 181-31 Rehde 181-27 Olson et al. 179-1 springs are connected to the center of said diaphragm lo STEPHEN J TOMSKY Primary Examiner.

while the others to the positions on said diaphragm. 

1. A REVERBERATION FLAT SPEAKER WHEREIN A FLAT DIAPHRAGM IS SECURED AROUND THE PERIPHERY THEREOF TO A SUPPORTING FRAME CHARACTERIZED IN THAT ONE ENDS OF A PLURALITY OF SPRINGS ARE CONNECTED TO THE CENTER OF SAID DIAPHRAGM WHILE THE OTHERS TO THE POSITIONS ON SAID DIAPHRAGM. 